The invention relates to a water meter with a metal housing which can be screwed into a connecting housing through which the water passes and which is disposed in a water pipeline. The metal housing presses a measurement insert, consisting of plastic and comprising a channel ring upper part and a channel ring lower part with a vane mounted there between, onto an outlet opening of the connecting housing to thereby form a seal.
Usually such water meters which generally comprise also a screen between the channel ring lower part and the connecting housing are constructed so that the metal housing, while being screwed in, is pressed onto a gasket surrounding the inlet opening of the connecting housing, the metal housing of the measurement insert at the same time pressing on the gasket around the outlet opening of the connecting housing. As a result, however, the entering water also comes into contact with the metal housing so that, even if brass or other materials are used for this purpose, or if surface-coating with chromium or nickel are employed, corrosion cannot be excluded.